초록
The effects of different epoxy resin(EP) and polyurethane (PU) blend composition ratios on cure kinetics and thermal stability were studied with DSC and TGA. In this work. 20 phr of DDM (4,4'-diamino diphenyl methane) was used as a curing agnet for epoxy resin and the content of EP/PU was varied within 100/0∼100/60 phr. Conversion (α), cure activation energy ($E_{a}$), and glass transition temperature ($T_{g}$) were determined by dynamic and isothermal DSC. As a result, both α and $E_{a}$ were increased at 40 phr of PU, and $T_{g}$ peaks of EP/PU were closest at 40 phr of PU. From the TGA results of EP/PU blend system, the thermal stability based on initial decomposed activation energy ($E_{a}$) was investigated. The thermal stability decreased with increasing the amount of PU, up to 40 phr of PU. These results could be explained by the increase in reactivity between the hydroxyl group in EP and isocyanate group in PU, resulting in an increase in the crosslinking density.
